1. Field of the Invention
The present invention relates to a navigation system for carrying out a navigation operation by using map data recorded in a record medium, and more particularly relates to a navigation system having a hard disc for storing the map data.
2. Description of the Related Art
There is a navigation system, which has a DVD-ROM (DVDxe2x80x94Read Only Memory) drive or a CD-ROM (Compact Discxe2x80x94Read Only Memory) drive, reads map data stored in a DVD-ROM or a CD-ROM as a record medium, and carries out a navigation operation. When carrying out the navigation operation, the navigation system detects a self-car position, reads the map data around the car from the record medium, and then displays a map picture generated on the basis of the map data together with a mark indicative of the self-car position on a display screen.
By the way, a record medium such as a DVD-ROM or the like is available in which music data and video data are recorded in a format of DVD-Video or DVD-Audio. Thus, it is desired to perform a reproduction of such a record medium during a car driving operation. However, the above-mentioned navigation system requires that the record medium in which the map data is stored is always inserted in the DVD-ROM drive or the like during the navigation operation. Namely, the DVD-ROM drive or the like is occupied by the record medium for the navigation operation. Hence, it is difficult to use the DVD-ROM drive or the like for another purpose such as a reproduction of the music data or video data.
On the other hand, it may be considered that the navigation system is equipped with, for example, a hard disc, as a non-volatile memory having a large capacity, besides the record medium. If the entire data of the DVD-ROM or the like is perfectly installed in the hard disc, and then the map data is read from the hard disc at a time of the navigation operation, the DVD-ROM or the like can be used for another purpose. Also, since an access speed for the hard disc is very fast, this has a merit from the viewpoint of a fast drawing on a display screen.
However, it takes a considerable time to carry out an installation operation from the record medium, such as the DVD-ROM or the like, to the hard disc. Also, this operation is troublesome for a user. Moreover, the DVD-ROM has a large capacity. For example, it has 4.7 Gigabytes in a case of a one-surface one-layer type, and it has 8.5 Gigabytes in a case of a one-surface two-layer type. Thus, correspondingly to a storage capacity or a memory capacity thereof, it is necessary to reserve a large storage area in the hard disc. Hence, when the hard disc is used for another purpose, this brings about enormous uselessness.
On the other hand, it may be considered that the map data is transferred from the record medium, such as the DVD-ROM or the like, to the hard disc during the navigation operation as the occasion demands, the processing performance of the navigation system is extremely dropped. That is, if a CPU of the navigation system always controls the transferring process, its process load becomes excessive. For example, a trouble is induced in the displaying process at a time of the navigation operation. Moreover, if the transfer is once carried out through a buffer, an inner bus is occupied, so that a trouble is induced even in another data transferring operation. In this way, the process of transferring the map data to the hard disc as mentioned above cannot be freely carried out because of a restriction or limitation on the process in the navigation system, which is a problem.
The present invention is proposed in view of the above mentioned problems. It is therefore an object of the present invention to provide a navigation system, which has a hard disc and can automatically transfer map data required for the navigation operation to the hard disc, without applying an excessive load on a CPU and without giving a bad influence on another process.
The above object of the present invention can be achieved by a first navigation system of the present invention provided with: a present position detecting device for detecting a present position; a first memory device for reading map data from a record medium in which the map data is recorded; a second memory device of non-volatile type, to which the map data can be written and from which the map data can be read; a navigation controlling device for controlling a navigation operation in correspondence with the detected present position by using the map data, and sending a transfer command to transfer the map data from the first memory device to the second memory device at a predetermined timing; and a transfer interface for controlling an operation of reading the map data from the record medium by the first memory device and an operation of transferring the map data to the second memory device, in accordance with the sent transfer command.
According to the first navigation system of the present invention, the navigation system is provided with the first memory device using the DVD-ROM, CD-ROM or the like, and the second memory device such as the hard disc or the like. The navigation controlling device sends the transfer command of the map data to the transfer interface at the predetermined timing while controlling the navigation operation in correspondence with the present position such as a self-car position. The transfer interface controls in accordance with the received transfer command so that the map data is read from the record medium by the first memory device, and is then transferred to the second memory device.
Therefore, in case that the map data is transferred to the second memory device, even if the record medium is not always set in the first memory device, the navigation operation can be continued. Further, since the map data is automatically transferred by the transfer command, and since it is not necessary for the navigation controlling device such as a CPU to intervene in the transferring process itself afterward, it is possible not to increase the processing load on the navigation controlling device and perform the processes necessary for the navigation operation smoothly. Thus, it is possible to efficiently use the map data by performing the transferring process without influencing the process of the navigation system.
In one aspect of the first navigation system of the present invention, the map data read from the record medium by the first memory device is sent through the transfer interface to the second memory.
According to this aspect, upon transferring the map data, the transfer interface obtains the map data read from the first memory device and transfers it as it is to the second memory device. Thus, since the map data is not passed through the internal bus etc., and is transferred by the transfer interface, the input and output of the data through the internal bus etc., required for another process is not interrupted.
In another aspect of the first navigation system of the present invention, the transfer interface comprises: a command converting device for converting a type of the sent transfer command to thereby generate a command, which is identifiable by the first memory device and the second memory device; and a transfer controlling device for controlling the operation of transferring the map data from the first memory device to the second memory device, on the basis of the generated command.
According to this aspect, upon transferring the map data, the transfer interface converts the type or format of the received transfer command and thereby generates the command based on the predetermined interface standard. Then, the transfer interface reads the map data from the fist memory device in accordance with this command, and then transfers and stores it into the second memory device. Thus, since the navigation controlling device does not have to control each of the memory devices individually and since the transfer command is automatically converted into the desired command, the load of the process accompanied by the navigation control is further reduced.
In this aspect of having the command converting device, the transfer interface may be further provided with a buffer memory device for transiently storing the map data, and the transfer controlling device may control the operation of transferring the map data from the first memory device to the buffer memory device and an operation of transferring the map data from the buffer memory device to the second memory device, on the basis of the generated command.
By constituting in this manner, upon transferring the map data, the transfer interface reads the map data from the first memory device and transiently stores it in the buffer memory device. In succession, the transfer interface reads the map data from the buffer memory device, and transfers and stores it to the second memory device. Since the map data is transferred through the buffer memory device, it is possible to transfer the map data surely at the desirable timing.
In the aspect of having the command converting device, the transfer controlling device may divide the map data into a plurality of unit data each comprising a predetermined unit data amount and transfers the map data by repeating an operation of transferring the unit data by a plurality of times.
By constituting in this manner, the transfer interface device can be connect with the first memory device and the second memory device by using a general interface standard, so that it is possible to easily control the whole transfer data amount by changing the number of times of the transferring operation of transferring the unit data.
In the aspect of having the command converting device, the command converting device may generate a plurality of commands by converting a type of the sent transfer command.
By constituting in this manner, since a plurality of commands are generated in response to the transfer command and since the transferring operation of the first memory device and the second memory device is controlled by those commands, it is not necessary for the navigation controlling device to instruct detailed processes in the transferring operation individually. Thus, the processes can be simplified.
In the aspect of having the command converting device in which the map data is divided into a plurality of unit data, the predetermined unit data amount may be substantially equal to a storage capacity of the buffer memory device.
By constituting in this manner, since the transfer interface controls the transferring operation by using the buffer memory device having the storage capacity substantially equal to the unit data amount, it is possible to improve the cost reduction by limiting the storage capacity of the buffer memory to the minimum level.
In the aspect of having the command converting device and the buffer memory device, the transfer interface may be further provided with an address generating device for generating an address for the transfer controlling device to access the buffer memory device.
By constituting in this manner, when the transfer controlling device controls the transferring operation, the predetermined address is generated by the address generating device, so that this address of the buffer memory device is accessed to thereby perform inputting and outputting the transfer data. Thus, it is enough that the transfer controlling device informs the address generating device of the presence or absence of the transferring operation and the transfer data amount, and the transferring operation can be simplified by removing the troublesome process such as an address calculation or the like.
In the aspect of having the command converting device, the transfer controlling device may output a signal, which is to identify an end of the operation of transferring the map data, to the navigation controlling device.
By constituting in this manner, at the timing when the transferring operation of the map data by the transfer interface is ended, the predetermined signal such as an interrupt signal etc., from the transfer controlling device is outputted. Then, the navigation controlling device, which has received this predetermined signal, can judge the end of the transferring operation. Therefore, after the navigation controlling device finishes the transferring operation, another process can be immediately performed in succession, so that the navigation operation can be made speedy.
In another aspect of the first navigation system of the present invention, the second memory device is capable of writing and reading the map data at an access speed faster than that of the first memory device.
According to this aspect, since the access speed of the second memory device is higher than that of the first memory device, it is possible to read out the map data from the second memory device for a shorter time period in accordance with the read command after the map data is transferred, so that the speedy navigation operation can be performed.
In this aspect, the second memory device may be provided with a hard disc device.
By constituting in this manner, since the hard disc device is used as the second memory device, it is possible to utilize the second memory device by transferring the map data to the second memory device, which is speedily accessible, which has a large storage capacity and whose flexibility is high.
In another aspect of the first navigation system of the present invention, a plurality of block map data, which are obtained by dividing a whole map for each unit block, are recorded in the record medium, and the transfer interface reads the block map data and transfers the read block map data to the second memory device.
According to this aspect, since the map data recorded in the record medium comprises a set of the block map data as for each unit block, which are obtained by dividing the whole map for each unit block. Then, the transfer interface transfers the respective block map data. Thus, the transfer interface can perform the transferring process of the map data uniformly. Therefore, since the storage capacity of each memory device and the generation of the command may be performed in accordance with a constant pattern, the control can be easily performed.
In this aspect in which the whole map is divided for each unit block, the transfer interface may be further provided with a buffer memory device, which has a storage capacity capable of storing at least one block map data, for transiently storing the block map data.
By constituting in this manner, the transferring process by the transfer interface is performed in such an order that one block map data is read out and is transiently stored in the buffer memory device, and after that, one block map data is read out from the buffer memory device and is then transferred. Thus, it is possible to transfer the map data in the necessary amount by repeating the same transferring operation with respect to each block map data. Hence, the transferring operation can be easily performed, and the storage capacity of the buffer memory device can be restrained.
Also, in the aspect in which the whole map is divided for each unit block, the navigation controlling device may judge whether or not each block map data to be transferred is already stored in the second memory device, and may control the transfer interface to transfer the block map data which is not judged to be stored in the second memory device yet.
By constituting in this manner, when the navigation controlling device transfers the block map data, the presence or absence of the block map data in the second memory device is judged, and, only if the block map data is not stored, the transfer command as for this block map data is sent to the second memory device. Therefore, by avoiding the useless transferring process, it is possible to perform the transferring process speedily.
Also in the aspect in which the whole map is divided for each unit block, the navigation controlling device may control the transfer interface to transfer a plurality of block map data corresponding to a plurality of peripheral unit blocks with respect to one unit block including the present position as a standard.
By constituting in this manner, the navigation controlling device transmits the transfer command as for the block map data corresponding to the unit blocks surrounding the present position with respect to one unit block including the present position as a standard. Therefore, it is possible to transfer the block map data to the second memory device in advance as for the unit blocks where the present position may be positioned in a near future at a high possibility.
Also in the aspect in which the whole map is divided for each unit block, the navigation controlling device may control the transfer interface to transfer a plurality of block map data corresponding to a plurality of unit blocks including an optimal route from the present position to a destination.
By constituting in this manner, when the optimal rout to the desired destination is set, the navigation controlling device transmits the transfer command as for the block map data corresponding to the unit blocks overlapped with the optimal route from the present position to the destination. Thus, it is possible to transfer the block map data in advance to the second memory device as for the unit blocks where the present position may be scheduled to be positioned in the near future.
In another aspect of the first navigation system of the present invention, the navigation controlling device controls the transfer interface to transfer the map data corresponding to a predetermined area defined in accordance with the detected present position.
According to this aspect, the predetermined area is defined in accordance with the present position, which is detected by the present position detecting device, and the map data corresponding to this area is read out. Then, the transfer command is sent by the navigation controlling device at the predetermined timing. Thus, since the transfer target can be limited, it is possible to speedily complete the transferring operation. Further, since the possibility of the transfer becomes the higher with respect to the area where the present position may be positioned in the near future at the higher possibility. Therefore, the usage value of the map data stored in the second memory device is improved.
In another aspect of the first navigation system of the present invention, the navigation controlling device sends the transfer command each time when a movable body, the present position of which is detected, is moved for a predetermined distance.
According to this aspect, the navigation controlling device sends the transfer command to the transfer interface at the timing when the present position is moved for the predetermined distance, and the transferring operation of the map data is performed as described above in accordance with this transfer command. Thus, since the transferring operation can be performed easily in conjunction with the timing approximately when the predetermined area to be the transfer target is changed, it is possible to perform the transferring operation smoothly.
In another aspect of the first navigation system of the present invention, the navigation controlling device sends a read command to read the map data as the transfer command, and the transfer interface reads the map data from the first or second memory device in accordance with the sent read command.
According to this aspect, the navigation controlling device sends the read command to the transfer interface so as to obtain the map data required for the navigation operation for example. The transfer interface, which has received this read command, reads out the necessary map data from the first memory device or the second memory device. Thus, it is possible to commonly use the transfer interface for the reading process without the necessity of another reading device, so that it is possible to perform the comfortable navigation operation by using the map data without introducing the complexity of the whole structure.
The above object of the present invention can be also achieved by a second navigation system provided with: a present position detecting device for detecting a present position; a first memory device for reading map data from a record medium in which the map data is recorded; a second memory device of non-volatile type, to which the map data can be written and from which the map data can be read; a transfer interface for controlling an operation of reading the map data from the record medium by the first memory device or the second memory device, in accordance with a read command to read the map data; and a navigation controlling device for controlling a navigation operation in correspondence with the detected present position by using the map data, which is read under a control of the transfer interface, and sending the read command at a predetermined timing.
According to the second navigation system of the present invention, the navigation controlling device sends the transfer command of the map data to the transfer interface at the predetermined timing while controlling the navigation operation in correspondence with the present position such as a self-car position. The transfer interface controls in accordance with the received transfer command so that the map data is read from the record medium by the first memory device or the second memory device, and the navigation operation is performed by using this read map data for the displaying process or the like, under the control of the navigation controlling device. Therefore, it is possible to perform the navigation operation smoothly while restricting the process load on the navigation controlling device such as a CPU, by obtaining the map data, without performing complex processes by virtue of the read command.
In one aspect of the second navigation system of the present invention, the read command is appended with identification information, which identifies whether or not the map data is to be read from the record medium by the first memory device or the second memory device.
According to this aspect, the identification information is obtained from the read command, and the map data is read from the record medium by the first memory device or the second memory device, which is identified by this identification information. Thus, it is possible to easily identify the memory device from which the map data is to be read, and it is possible to simplify the process of reading the map data even more.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.